Massimiliano Simi

Swallowable Medical Devices for Diagnosis and Surgery: The State of the Art

Abstract The first wireless camera pills created a revolutionary new perspective for engineers and physicians, demonstrating for the first time the feasibility of achieving medical objectives deep within the human body from a swallowable, wireless platform. The approximately 10 years since the first camera pill has been a period of great innovation in swallowable medical devices. Many modules and integrated systems have been devised to enable and enhance the diagnostic and even robotic capabilities of capsules working within the gastrointestinal (GI) tract. This article begins by reviewing the motivation and challenges of creating devices to work in the narrow, winding, and often inhospitable GI environment. Then the basic modules of modern swallowable wireless capsular devices are described, and the state of the art in each is discussed. This article is concluded with a perspective on the future potential of swallowable medical devices to enable advanced diagnostics beyond the capability of human visual perception, and even to directly deliver surgical tools and therapy non-invasively to interventional sites deep within the GI tract.

Advanced Technologies for Gastrointestinal Endoscopy

The gastrointestinal tract is home to some of the most deadly human diseases. Exacerbating the problem is the difficulty of accessing it for diagnosis or intervention and the concomitant patient discomfort. Flexible endoscopy has established itself as the method of choice and its diagnostic accuracy is high, but there remain technical limitations in modern scopes, and the procedure is poorly tolerated by patients, leading to low rates of compliance with screening guidelines. Although advancement in clinical endoscope design has been slow in recent years, a critical mass of enabling technologies is now paving the way for the next generation of gastrointestinal endoscopes. This review describes current endoscopes and provides an overview of innovative flexible scopes and wireless capsules that can enable painless endoscopy and/or enhanced diagnostic and therapeutic capabilities. We provide a perspective on the potential of these new technologies to address the limitations of current endoscopes in mass cancer screening and other contexts and thus to save many lives.

Design, Fabrication, and Testing of a Capsule With Hybrid Locomotion for Gastrointestinal Tract Exploration

This paper describes a novel solution for the active locomotion of a miniaturized endoscopic capsule in the gastrointestinal (GI) tract. The authors present the design, development, and testing of a wireless endocapsule with hybrid locomotion, where hybrid locomotion is defined as the combination between internal actuation mechanisms and external magnetic dragging. The capsule incorporates an internal actuating legged mechanism, which modifies the capsule profile, and small permanent magnets, which interact with an external magnetic field, thus imparting a dragging motion to the device. The legged mechanism is actuated whenever the capsule gets lodged in collapsed areas of the GI tract. This allows modification of the capsule profile and enables magnetic dragging to become feasible and effective once again. A key component of the endoscopic pill is the internal mechanism, endowed with a miniaturized brushless motor and featuring compact design, and adequate mechanical performance. The internal mechanism is able to generate a substantial force, which allows the legs to open against the intestinal tissue that has collapsed around the capsule body. An accurate simulation of the performance of the miniaturized motor under magnetic fields was carried out in order to define the best configuration of the internal permanent magnets (which are located very close to the motor) and the best tradeoff operating distance for the external magnet, which is responsible for magnetically dragging the capsule. Finally, a hybrid capsule was developed generating 3.8 N at the tip of the legged mechanism and a magnetic link force up to 135 mN. The hybrid capsule and its wireless control were extensively tested in vitro, ex vivo , and in vivo, thus confirming fulfilment of the design specifications and demonstrating a good ability to manage collapsed areas of the intestinal tract.

Magnetic Torsion Spring Mechanism for a Wireless Biopsy Capsule

The authors present a novel magnetomechanical elastic element that can be loaded remotely by varying the magnetic field surrounding it and that is able to store and release mechanical energy upon external triggering. The magnetic torsion spring (MTS) is used as the core component of a self-contained miniature biopsy capsule (9 mm in diameter and 24 mm long) for random tissue sampling in the small bowel. Thanks to the MTS concept, the biopsy mechanism can be loaded wirelessly by a magnetic field applied from outside the body of the patient. At the same time, magnetic coupling guarantees stabilization against the small bowel tissue during sampling. Extreme miniaturization is possible with the proposed approach since no electronics and no power supply are required onboard. [DOI: 10.1115/1.4025185]

Magnetically Activated Stereoscopic Vision System for Laparoendoscopic Single-Site Surgery

In this paper, the authors present an innovative vision platform for laparoendoscopic single-site (LESS) surgery based on a wired and magnetically activated 5-degrees-of-freedom robot with stereovision. The stereoscopic vision module, developed using two off-the-shelf cameras and a light emitting diodes lighting system, is mounted on the robot tip. An autostereoscopic screen is adopted to display the surgical scenario as an alternative to 3-D helmets or polarizing glasses. A rough position of the stereocamera can be determined along the abdominal wall by dragging the robot with a set of external permanent magnets (EPMs). Once the camera is set in the desired position, the EPMs provide fixation, while the internal mechanism allows fine tilt adjustment. Considering the deformable round shape of the insufflated abdomen wall and in order to replicate the precise roll motion usually provided by the endoscopists hands, this prototype embeds an actuated mechanism that adjusts the stereocamera horizon and thus prevents any visual discomfort. Finally, the platform was preliminarily tested in vivo in a LESS scenario, demonstrating its advantages for eliminating potential conflicts with the operative tools and enabling the introduction of an additional instrument through the same access port used for stereoscopic vision.

Magnetic Levitation camera robot for endoscopic surgery

A wired miniature surgical camera robot with a novel Magnetic Levitation System (MLS) was modeled, designed and fabricated. A simple analysis and a theoretical model were developed in order to describe and predict basic behavior for different structural parameters of the system. The robot is composed of two main parts (head and tail) linked by a thin elastic flexible joint. The tail module embeds two magnets for anchoring and manual rough translation. The head module incorporates two motorized donut-shaped magnets and a miniaturized vision system at the tip. The MLS can exploit the external magnetic field to induce a smooth bending of the robotic head, guaranteeing a high span tilt motion of the point of view (0°–80°). The device is 100 mm long and 12.7 mm in diameter. Use of such a robot in single port or standard multiport laparoscopy could enable reduction of number/size of ancillary trocars, and/or increase the number of working devices that can be deployed, thus paving the way for multiple point of view laparoscopy.

Autostereoscopic Three-Dimensional Viewer Evaluation Through Comparison With Conventional Interfaces in Laparoscopic Surgery

In the near future, it is likely that 3-dimensional (3D) surgical endoscopes will replace current 2D imaging systems given the rapid spreading of stereoscopy in the consumer market. In this evaluation study, an emerging technology, the autostereoscopic monitor, is compared with the visualization systems mainly used in laparoscopic surgery: a binocular visor, technically equivalent from the viewer’s point of view to the da Vinci 3D console, and a standard 2D monitor. A total of 16 physicians with no experience in 3D interfaces performed 5 different tasks, and the execution time and accuracy of the tasks were evaluated. Moreover, subjective preferences were recorded to qualitatively evaluate the different technologies at the end of each trial. This study demonstrated that the autostereoscopic display is equally effective as the binocular visor for both low- and high-complexity tasks and that it guarantees better performance in terms of execution time than the standard 2D monitor. Moreover, an unconventional task, included to provide the same conditions to the surgeons regardless of their experience, was performed 22% faster when using the autostereoscopic monitor than the binocular visor. However, the final questionnaires demonstrated that 60% of participants preferred the user-friendliness of the binocular visor. These results are greatly heartening because autostereoscopic technology is still in its early stages and offers potential improvement. As a consequence, the authors expect that the increasing interest in autostereoscopy could improve its friendliness in the future and allow the technology to be widely accepted in surgery.

Fine Tilt Tuning of a Laparoscopic Camera by Local Magnetic Actuation: Two-Port Nephrectomy Experience on Human Cadavers

Background. The magnetic surgical camera is an emerging technology having the potential to improve visualization without taking up port site space. However, tilting the point of view downward/upward can be done only by constantly applying a pressure on the abdomen. This study aims to test the hypothesis that the novel concept of local magnetic actuation (LMA) is able to increase the tilt range available for a magnetic camera without the need for deforming the abdominal wall. The hypothesis that 2-port laparoscopic nephrectomy in fresh tissue human cadavers could be performed by using the LMA camera is also tested. Methods. First, the 2 cameras were separately inserted, anchored, and moved inside the inflated abdomen. Tilting angles were quantified by image analysis while intra-abdominal pressure changes were monitored. Then, 5 two-port nephrectomies were performed by using the LMA camera while collecting quantitative outcomes. Results. The magnetic camera required a constant pressure on the magnetic handle to achieve an average ±20° tilt from the horizontal position, with an average of 7 mm Hg loss of intra-abdominal pressure. The LMA camera allowed for 75° of tilt from the horizontal position with a resolution of ±1°, without any need to deform the abdomen. All the nephrectomies were completed successfully within an average time of 11 minutes. Conclusion. LMA is an effective strategy to provide magnetic cameras with wide-range and high-resolution vertical motion without the need to deform the abdominal wall.

Trans-abdominal Active Magnetic Linkage for robotic surgery: Concept definition and model assessment

The novel concept of Trans-abdominal Active Magnetic Linkage for laparoendoscopic single site surgery has the potential to enable the deployment of a bimanual robotic platform trough a single laparoscopic incision. The main advantage of this approach consists in shifting the actuators outside the body of the patient, while transmitting a controlled robotic motion by magnetic field across the abdomen without the need for dedicated incisions. An actuation mechanism based on this approach can be comprised of multiple anchoring and actuation units, mixed depending upon the specific needs. A static model providing anchoring and actuation forces and torques available at the internal side of the magnetic link was developed to provide a tool to navigate among the many possibilities of such an open ended design approach. The model was assessed through bench top experiments, showing a maximum relative error of 4% on force predictions. An example of a single degree of freedom manipulator actuated with the proposed concept and compatible with a 12-mm access port is able to provide an anchoring force of 3.82 N and an actuation force of 2.95 N.

Magnetic Mechanism for Wireless Capsule Biopsy

One of the main diagnostic limitations of current gastrointestinal (GI) capsule endoscopes is that they cannot get biopsies, thus requiring follow-up with flexible endoscopy whenever a suspicious lesion is identified. The ability of getting biopsies from a wireless capsule would save time and costs associated with the procedure, reducing at the same time invasiveness and discomfort for the patient. The Crosby capsule, designed in 1957, exploits a small tether to suck tissue, to activate spring-loaded knife and to manage device retrieval. However, invasiveness of the procedure is still relevant and requires sedation [1]. Two compact mechanisms have been recently proposed for wireless biopsy. The first takes advantage of a spring actuated rotational razor [2], while the second exploits Shape Memory Alloy (SMA) to actuate a micro-biopsy spike [3]. Due to the harsh environment of the GI tract and the absence of stabilization during sampling, both these devices have a limited efficacy. In order to improve efficacy while reducing capsule size, we propose a completely magneto-mechanical mechanism which does not require onboard batteries and actuators.